1. Field of the Invention
The present invention generally relates to connecting two or more Printed Circuit Boards (PCBs) and more specifically to providing a controlled impedance connection between the two or more PCBs.
2. Description of the Related Art
Most electronic devices today contain one or more Printed Circuit Boards (PCBs). A PCB is used to mechanically support and electrically connect components of a device using conductive pathways called traces. For example, a computer usually contains a PCB called the motherboard. The motherboard contains the essential components of the computer such as the microprocessor and main memory, along with other basic components. The components may be housed in sockets and connected to each other using the traces.
During assembly of electronic devices, one or more PCBs may be secured to a device frame or chassis. Securing the PCBs usually involves fastening the PCB to the device chassis, using screws. The PCB is usually secured on one or more standoffs. Placing the PCB on a standoff ensures airflow along both surfaces of the PCB, thereby allowing cooling during operation of the device. The standoffs also prevent undesired contact between active circuits of the PCB and other device components.
Furthermore, one or more PCBs may be connected to each another to facilitate communication between the PCBs. Connecting two or more PCBs may involve providing a connector to connect circuits on the PCBs. Typically, the connectors include individual conductive paths housed in a plastic body. At one end of the conductive path a first pin coupled with the conductive path may be configured to connect to a connector pad or trace line of a first PCB. At the other end of the conductive path a second pin coupled with the conductive path may be configured to connect to a connector pad or trace line of a second PCB, thereby establishing an electrical connection between the first and second PCBs. One problem with prior art connectors is that the connectors typically provide for planar connection of the PCBs, thereby taking up valuable space in a device.
Another problem with prior art connectors is that the impedance of a conductive line in a connector may not match the impedance of a circuit on the PCB. Such impedance mismatches result in undesired reflection of signals transferred between PCBs at the interface of a circuit of a PCB and the connector. Reflections can distort the signal transferred between the PCBs and result in transmission failures. Furthermore, in order to prevent transmission errors caused by signal reflection, the speed at which PCB circuits operate may have to be limited. With growing demand for increasingly faster devices, the limitations imposed by the connectors can become unacceptable.
Another problem with prior art connectors is that the connectors may carry significant common mode currents. Such common mode currents are a primary source of electromagnetic radiation in a device. Electromagnetic radiation may interfere with the operation of circuits in the device and adversely affect the reliability of electronic systems.
Therefore, what is needed are methods, systems, and articles of manufacture for providing a controlled impedance connection between PCBs.